1. Field of the Invention
Embodiments of the present invention generally relate to pumps. More specifically, and not by way of limitation, embodiments of the present invention relate to positive displacement pumps for the circulation of fluids.
2. Description of Related Art
Many natural and manmade fluids contain molecules that can be damaged or destroyed by excessive shearing strains or stagnation that can occur in devices that attempt to pump these fluids. Fluids containing molecules with high molecular weights such as proteins, long stranded synthetic polymers, DNA, RNA, or fluids such as blood, which contain concentrations of delicate cells, are especially susceptible to being compromised by many conventional pumping techniques.
Typical axial flow and centrifugal pumps operate by rotating an impeller at very high speeds, often exceeding 12,000 RPM. The shearing stresses that can arise at these velocities can strain larger fluid molecules until they break, leading to destruction or undesirable alteration of the pumping medium. For instance, it is well documented that the pumping of blood using centrifugal and axial flow pumps shears the phospholipid bilayer of erythrocytes and platelets to the point of lysing the cells and releasing their cytosolic proteins and organelles into the blood stream. This phenomenon, known as hemolysis, is an issue in the field of artificial blood circulation because the releasing of hemoglobin into the blood stream can cause kidney failure in patients who receive this blood. Thus, there is useful need for pump designs that can provide fluid circulation without damaging a delicate pumping medium such as blood.
Further objects and advantages of this system and method will become apparent from a consideration of the drawings and ensuing description.